This come across on another thread, but I've heard about this technique somewhere else. Does adding your LME the last 20 minutes do anything to the brew? Doesn't it need to be boiled for at least an hour? Won't the chemistry be different somehow?

It'll reduce the caramelization, resulting in a lighter-colored beer. For sanitation, you only need to boil for fifteen or twenty minutes. The other reason for boiling the wort is to get a hot break, but that's less an issue with extract (which I believe has had most of the break removed during the manufacturing process, at least according to the interview I heard recently).

Since your hops will be boiled for most of the time in a lower-gravity wort, utilization will be higher.

I've been doing a late-extract addition to my most recent batches (both partial/mostly-mash). I'm using DME, but the same factors apply to LME.

"I'm kind of toasted. But I looked at my watch and it's only 6:30 so I can't stop drinking yet." - Yooper's Bob"Brown eye finally recovered after the abuse it endured in Ptown last weekend, but it took almost a full week." - Paulie"no, he just doesn't speak 'stupid'. i, however, am fluent...." - motobrewer"... I'll go both ways." - Melana

This come across on another thread, but I've heard about this technique somewhere else. Does adding your LME the last 20 minutes do anything to the brew? Doesn't it need to be boiled for at least an hour? Won't the chemistry be different somehow?

You really only need to boil the extract long enough to sanitize it, so 15 minutes should be plenty. (Actually, canned extract should already be sanitary, so you technically don't need to boil it at all.... This is the philosophy behind the 'no-boil' pre-hopped extracts - just add water and yeast!)

But... addint the extract late will change a few things:

(1) the beer will be lighter in color. The longer you boil it, the more the sugars caramalize, and the darker it gets.

(2) bittering hops that are put into the kettle before the extract is added will see their utilization will go way up. Hop utilization is a function of the liquid's density; the thicker the liquid, the less utilization.

So, it's got nothing to do with the brewing chemical magic? I mean, I can understand hops utilization. But, there is no affect on taste when the LME and hops are boiling around in the pot for about an hour? It's just going to change color? Then why the hour boils with extracts???

Nope....no magical chemical reactions. So to speak. Basically you boil the oils out of the hops. The longer you boil the hops the more bitter they become. That is a magical chemical reaction, you need to use 50% less bittering hops if you add extract late, so that your brew will not be too bitter.

"I'm kind of toasted. But I looked at my watch and it's only 6:30 so I can't stop drinking yet." - Yooper's Bob"Brown eye finally recovered after the abuse it endured in Ptown last weekend, but it took almost a full week." - Paulie"no, he just doesn't speak 'stupid'. i, however, am fluent...." - motobrewer"... I'll go both ways." - Melana

Walker and the_bird already answered the flavor question. The longer you boil your extract the more caramelization you'll get (a good thing in some beers), but again you're worried about hop utilization, so you'll only be concentrated boiling for darker less hoppy beers.

Nope....no magical chemical reactions. So to speak. Basically you boil the oils out of the hops. The longer you boil the hops the more bitter they become. That is a magical chemical reaction, you need to use 50% less bittering hops if you add extract late, so that your brew will not be too bitter.

Is that true? I thought you added the same hops as the recipe calls for, and with late extract your utilization is closer to "normal" than with straight concentrated boil? My impression being that without late extract you will typically be getting less of the bittering hops you were hoping for.

Somewhere I read, it might have been that BYO article, that the hops will utilize 75% of their oils within the first 30 minutes of boiling......so YOU know what I was thinking? Cut your 60 minute boils to half! Boil water, toss the hops, with about 10 to go, throw in the LME and the finishing hops. Since your not going to get full utilization of the hops, then adding the LME late, should almost balance out.